Production of photographic prints



Patented Oct. 3, 1944 PRODUCTION OF PHOTOGRAPHIC PRINTS Robert Thomas Lewis and Ross Inglis Lewis, Manchester, England No Drawing. Application February-26, 1942, Se-

rial No. 432,526. In Great Britain December 14,

This invention relates to the production of photographs and has for its object to provide an improved process and means for use therein for obtaining toned, tinted, dyed or shaded prints or prints differing from the original negative.

Our invention comprises a resist or reserve (which is light, water, acid, bleach, fixer and developer proof) adapted to be detachably secured to the negative, the printing paper, lantern slide or the like in the form of a paste or solution or in the form of a sheet, such resist or reserve comprising rubber preferably in the form of pale crepe rubber which acts as a binding agent and liquid resist, a colour body such as fast helio red to give colour depth and assist in preventing light penetration, a pulverulent body which gives opacity such as titanium dioxide, a body such as paraflin wax to give smooth flowing properties to the mixture, and with if desired a preservative, such as magnesium dioxide which maintains the mix in serviceable condition for a long period. To produce a paste or solution, the mix or mastic is dissolved in a rubber solvent, such as carbon tetrachloride, but excludmg ammonia.

The invention further comprises the process of producing photographs in which the resist or reserve is applied to a selected part or parts of the negative after developing and fixing or to the photographic printing paper before or after the printing operation so that such part or parts is or are unaffected by light or by a subsequent toning, tinting, dyeing, shading or like operation applied to the whole negative or print and may thereafter when the resist or reserve has been removed be diflerently treated whilst other parts are protected by application thereto of the resist or reserve.

The invention further comprises the improved resist and the improved methods of using the same in the production of photographs as hereinafter described.

In one convenient application of the invention, the resist or reserve has the following composition, the parts being by weight.

The mixture or mastic is dissolved in 64 parts of carbon tetrachloride.

1 Claim. (Cl. 260-764) In one way of using the resist, it is applied by brush to part of a sensitized photographic sheet which is then exposed under a negative, developed, fixed and washed. The portion covered by the resist is unaffected. The resist can then be rubbed OE and the part thereunder may be exposed under a different negative, developed and fixed in the usual way. The part unaffected by the first exposure under the negative may have the resist removed before developing and fixing, when it will be finished in the basic colour of the printing paper.

In another example, the resist material is applied to a sheet of paper which constitutes a carrier, and can be cut to any desired shape to form a mask for a selected part or selected parts of a photographic printing paper. The resist is caused to adhere to the latter before it has dried upon the carrier or after damping with a rubber solvent. By the use of the carrier for the resist material, intricate designs or patterns can be masked for differential treatment. This masking is particularly useful in colour toning and tinting, and especially in multiple toning, tinting, dyeing and staining, where several separate masks can be applied and removed successively as the toning, tinting or like progresses.

In some cases where small areas are to be toned or tinted, this may be done locally by applying the resist around the area to be treated so as to make a pool of such area into which the bleacher and subsequently the sulphide solution or any other toner, tint or dye can be filled by' a brush, a squirt or small pump, such as a fountain pen filler.

In another application of the invention a mask such as before referred to is applied over large areas to be protected and then the finer outline is finished by carefully painting the resist solution around the mask.

The masks can be cut out to a particular shape in bulk by suitable means when a number of the same print has to be treated.

If desired the resist can be applied by means similar to a duplicating machine or by blocks or other printing devices. Where duplicating type machines are used, the resist in fluid form is printed on to the printing paper through a stencil. The edges of the resist pattern on the paper may be touched up or finished by hand, by brushing or otherwise if necessary.

Our resists can be used in the process of producing coloured prints by direct development by mother developers and colour formers to control the final colouring of the various parts of the picture or photograph.

The improved resist or reserve for use in photography consisting of-- Parts by weight Pale crepe rubber 48 t Fast helio red 8 Titanium dioxide l 2 Paraflin wax 1 Magnesium di e 1 l 5 dissolved in 64 parts of carbon tetrachloride.

ROBERT THOMAS LEWIS. ROSS INGLIS IrEWIS. 

